Hi,
If you are selling ebooks in the UK then these should be zero rated supplies. You can see guidance here:
E-publications
If you are selling these digital services to customers outside the UK then these should be outside the scope of VAT.
The place of supply of digital services
Please also see the guidance where you are selling these services via an online platform:
Digital portals, platforms, gateways and marketplaces
If the marketplace is charging your business from overseas and your business belongs in the UK then we would expect for the VAT to be accounted for on the reverse charge by your business. Please see the guidance below:
Reverse charge
If the marketplace are charging you from their branch in the UK then they would need to charge you UK VAT because of the place of supply rules. Please see below:
The place of supply rules for services
If you have been charged VAT correctly and this VAT has been incurred in the course of your business then the VAT can be treated as input tax if the conditions are met below:
Introduction to input tax
Thank you.